I get what you're saying. I do think, though, that when most thinkers from Hobbes to Goebbels identify something as the central problem of our current societal order, that we should take it seriously. This isn't counter to your point, but an elaboration of it. Right now, we're basically more free to say anything than we've ever been and I'm not exactly arguing against the current state of affairs. I will just surmise that the fact we're not seriously risking violence is because of something unrelated to speech, or ideas. Because all the same odious ideas that were motivating people in Weimar germany are having something of a hay day (at least compared to recent history). But we don't really see the same results. It's not because the ideas can't lead to the same results, but that something else is preventing it. I personally think that it's because most people just ain't cut out for that shit anymore. In this sense, the pussification of the western male has been a happy development. If we were our grandfathers, I think there would be blood running in the streets.
I have another tangent, though: it seems to me like freedom of speech has always been a proxy for something else. What if there were no restrictions on speech at all but you could never influence society with your words? I don't think most people would go for that (even though most of us will never say anything that will shape our world). So what is it a proxy for?
We can call it "pussification" or just civilization.
Our grandfathers, or atleast mine, didn't have much of a choice outside of violence. It's not like he was out there pushing for WW2, couple of spectacularly deranged individuals did. In his case, Soviets left no option beyond responding with violence.
Speech has a lot to do with it, because we have become more and more capable of discussing about our ideas, communicating with each other, coming to compromises which fit both parties, making outright conflict less and less necessary. My grandfather, for example, was not really a person that you could have communicated with. He held to rigid principles and if these were not obeyed, he responded with violence. But he was shaped into such a man because of violence he encountered, first in a Civil War, and then in a World War. His ways of behaving were a reaction to surrounding circumstances rather than a representation of our "base nature" or anything like that.
There is nothing comparable to what went down in Germany today and people who suggest that something of that sort is happening today, don't know anything about what went down. They don't know a damn thing about anything.
One of the problems with Nazism, for example, having become such a taboo, is that people just don't understand anything about them. They don't know what was driving them, which historical circumstances contributed to their rise, what they really believed in, and thus they just see Nazis everywhere even though they are nowhere. 1940's was the last time that the world has seen Nazis, everything else after that has just been angry young men LARPing.